(a) Technical Field
The present disclosure relates to a fuel cell separator with a gasket for improved sealing, and more particularly, to a fuel cell separator with a gasket that improves the contact pressure thereof.
(b) Background Art
As is well known in the art, a fuel cell stack includes a membrane electrode assembly (MEA) disposed at the innermost side thereof. The MEA includes a polymer electrolyte membrane through which protons may be moved, and catalyst layers, i.e. a cathode (air electrode) and an anode (fuel electrode), which are applied to both surfaces of the polymer electrolyte membrane such that hydrogen reacts with oxygen.
In addition, the fuel cell stack includes a gas diffusion layer (GDL) and a gasket which are sequentially stacked at the exterior of the electrolyte membrane, i.e. at the portion in which the cathode and the anode are disposed, a separator disposed at the exterior of the GDL and formed with a flow field through which fuel is supplied and water generated by reaction is discharged, and an end plate coupled to the outermost side thereof for supporting and fixing the above components. Accordingly, protons and electrons are generated by the oxidation reaction of hydrogen in the anode of the fuel cell stack. In particular, the generated protons and electrons move to the cathode through the respective electrolyte membrane and the separator. In the cathode, water is generated by the electrochemical reaction of the protons and electrons, which move from the anode, and oxygen in the air, and electric energy is simultaneously generated through the flow of electrons.
In the fuel cell stack, the gasket is attached to the separator to divide each unit cell of the fuel cell stack and functions to independently seal passages of hydrogen, coolant, air, formed on the surface of the separator. Further, to more smoothly perform the function of the gasket, the fuel cell stack is manufactured in consideration of the method of attaching the gasket to the separator and the selection of gasket materials.
In other words, the bonding structure between the separator and the gasket requires a passage sealing function for preventing hydrogen from coming into direct contact with air, a sealing function for preventing coolant from coming into contact with hydrogen and air, a sealing retention function for preventing fluids (e.g., air, hydrogen, and coolant) from flowing out to the outside, etc. In addition, the gasket disposed between the separators provides support force between the separators. The gasket may be manufactured integrally with each separator on both surfaces of the separators by injection molding. Particularly, the gasket may be manufactured to prevent working fluid from leaking due to characteristics of fuel cells in which airtightness (e.g., an airtight seal) is required for reactant gas and cooling fluid.
In connection with the fuel cell separator with the gasket for improved sealing, an apparatus of the related art includes gaskets integrated with separators by injection molding, and the gaskets integrated on both surfaces of the separators by injection molding are continuously connected, thereby forming one closed curve. In addition, the interface between the overall edge of each separator and each manifold is formed with a plurality of injection apertures through which an injection liquid for gasket passes, the injection liquid for gasket flows from one surface of the separator to the opposite surface thereof through the injection apertures, and thus, the gaskets are integrated throughout both surfaces of the separator by injection molding.
Specifically, the structure of a gasket formed at each of reaction and cooling surfaces of a conventional separator will be described with reference to FIGS. 1A-1B of the related art. Each of reaction surfaces 10 and 10′ of a separator illustrated in FIGS. 1A-1B is a portion in which a fuel cell reaction occurs. In the reaction surfaces 10 and 10′, manifolds 20, 20′, 22. 22′, 24, and 24′ which provide passages for air, coolant, and hydrogen are disposed, and reaction surface-side airtight lines 30a and 30a′ are formed to block the movement of reactant gas and cooling fluid. A plurality of gasket support portions 32a and 32a′ are formed in parallel from the airtight lines 30a and 30a′ to be spaced at predetermined intervals. In addition, the hydrogen or air introduced from cooling surfaces 12 and 12′ of the separator moves to the reaction surfaces 10 and 10′ through gas through-apertures 40 and 40′.
In addition, each of the cooling surfaces 12 and 12′ of the separator is a portion in which heat generated by a chemical reaction is removed. In the cooling surfaces 12 and 12′, manifolds 20, 20′, 22, 22′, 24, and 24′ which provides passages for air, coolant, and hydrogen are disposed, and cooling surface-side airtight lines 30b and 30b′ are formed to introduce cooling fluid. A plurality of gasket support portions 32b and 32b′ are formed in parallel from the airtight lines 30b and 30b′ to be spaced at predetermined intervals.
As illustrated in FIGS. 1A-1B, in the gasket, the positions of the cooling surface-side airtight lines 30b and 30b′ and the reaction surface-side airtight lines 30a and 30a′ differ from each other, and the gasket support portions 32b and 32b′ support the load of the gasket. Accordingly, the contact pressure of each airtight line between the gasket support portions 32b and 32b′ may deteriorate, and coolant may leak to the air manifolds 20 and 20′ or the hydrogen manifolds 24 and 24′.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.